Bottom Line:
Rhesus macaques inoculated with an AAV vector stably expressed 17-77 μg ml(-1) of fully functional rhesus eCD4-Ig for more than 40 weeks, and these macaques were protected from several infectious challenges with SHIV-AD8.Rhesus eCD4-Ig was also markedly less immunogenic than rhesus forms of four well-characterized bNAbs.Our data suggest that AAV-delivered eCD4-Ig can function like an effective HIV-1 vaccine.

ABSTRACTLong-term in vivo expression of a broad and potent entry inhibitor could circumvent the need for a conventional vaccine for HIV-1. Adeno-associated virus (AAV) vectors can stably express HIV-1 broadly neutralizing antibodies (bNAbs). However, even the best bNAbs neutralize 10-50% of HIV-1 isolates inefficiently (80% inhibitory concentration (IC80) > 5 μg ml(-1)), suggesting that high concentrations of these antibodies would be necessary to achieve general protection. Here we show that eCD4-Ig, a fusion of CD4-Ig with a small CCR5-mimetic sulfopeptide, binds avidly and cooperatively to the HIV-1 envelope glycoprotein (Env) and is more potent than the best bNAbs (geometric mean half-maximum inhibitory concentration (IC50)
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Figure 11: Extended Data for Figure 3 (IC80 values)The IC80 values from studies of Figs. 1b, 2a, 2b, and Extended Data Figs. 4–6 are plotted. The number of isolates resistant to 50 μg/ml of the indicated inhibitors are indicated on top. Geometric means are calculated for neutralized isolates and indicated with horizontal lines.

Mentions:
We further evaluated eCD4-Ig, eCD4-Igmim2, eCD4-IgQ40A,mim2 and the bNAb NIH45-46 using nearly every isolate reported to be resistant to either of the CD4bs antibodies NIH45-46 or 3BNC117 (Extended Data Figs. 4b and 5b). Both eCD4-Ig variants efficiently neutralized all 38 resistant isolates assayed with IC50s ranging from <0.001 μg/ml to 1.453 μg/ml. In contrast, 26 isolates in this panel were confirmed to be resistant to NIH45-46. 29 isolates and 18 isolates have been previously reported resistant to 3BCN117 and VRC01, respectively4,6. Fig. 3 and Extended Data Fig. 7 summarize the neutralization studies compiled from the experiments in Figs. 1 and 2, Extended Data Figs. 4–6, and from previous studies of VRC01 and 3BNC117 against the same isolates4. They show that the geometric mean IC50 and IC80 values of eCD4-Ig and its variants are less than 0.05 μg/ml (500 pM) and 0.2 μg/ml (2 nM), respectively, roughly 3–4 times lower than those of VRC01, NIH45-46, or 3BNC117. Importantly, our lead eCD4-Ig variant, eCD4-Igmim2, neutralized 100% of the isolates assayed at concentrations (IC50 < 1.5 μg/ml; IC80 < 5.2 μg/ml) likely sustainable in humans.

Figure 11: Extended Data for Figure 3 (IC80 values)The IC80 values from studies of Figs. 1b, 2a, 2b, and Extended Data Figs. 4–6 are plotted. The number of isolates resistant to 50 μg/ml of the indicated inhibitors are indicated on top. Geometric means are calculated for neutralized isolates and indicated with horizontal lines.

Mentions:
We further evaluated eCD4-Ig, eCD4-Igmim2, eCD4-IgQ40A,mim2 and the bNAb NIH45-46 using nearly every isolate reported to be resistant to either of the CD4bs antibodies NIH45-46 or 3BNC117 (Extended Data Figs. 4b and 5b). Both eCD4-Ig variants efficiently neutralized all 38 resistant isolates assayed with IC50s ranging from <0.001 μg/ml to 1.453 μg/ml. In contrast, 26 isolates in this panel were confirmed to be resistant to NIH45-46. 29 isolates and 18 isolates have been previously reported resistant to 3BCN117 and VRC01, respectively4,6. Fig. 3 and Extended Data Fig. 7 summarize the neutralization studies compiled from the experiments in Figs. 1 and 2, Extended Data Figs. 4–6, and from previous studies of VRC01 and 3BNC117 against the same isolates4. They show that the geometric mean IC50 and IC80 values of eCD4-Ig and its variants are less than 0.05 μg/ml (500 pM) and 0.2 μg/ml (2 nM), respectively, roughly 3–4 times lower than those of VRC01, NIH45-46, or 3BNC117. Importantly, our lead eCD4-Ig variant, eCD4-Igmim2, neutralized 100% of the isolates assayed at concentrations (IC50 < 1.5 μg/ml; IC80 < 5.2 μg/ml) likely sustainable in humans.

Bottom Line:
Rhesus macaques inoculated with an AAV vector stably expressed 17-77 μg ml(-1) of fully functional rhesus eCD4-Ig for more than 40 weeks, and these macaques were protected from several infectious challenges with SHIV-AD8.Rhesus eCD4-Ig was also markedly less immunogenic than rhesus forms of four well-characterized bNAbs.Our data suggest that AAV-delivered eCD4-Ig can function like an effective HIV-1 vaccine.

ABSTRACTLong-term in vivo expression of a broad and potent entry inhibitor could circumvent the need for a conventional vaccine for HIV-1. Adeno-associated virus (AAV) vectors can stably express HIV-1 broadly neutralizing antibodies (bNAbs). However, even the best bNAbs neutralize 10-50% of HIV-1 isolates inefficiently (80% inhibitory concentration (IC80) > 5 μg ml(-1)), suggesting that high concentrations of these antibodies would be necessary to achieve general protection. Here we show that eCD4-Ig, a fusion of CD4-Ig with a small CCR5-mimetic sulfopeptide, binds avidly and cooperatively to the HIV-1 envelope glycoprotein (Env) and is more potent than the best bNAbs (geometric mean half-maximum inhibitory concentration (IC50)
Show MeSH